Electric contact



Dec. 14, 1943. w. ARON ELECTRIC CONTACT Filed Feb. 11, 1942 PatentedDec. 14, 1943- UNITED STATES. PATENT, jorricr:

miaiil ittm Werner Aron, Dunstable, England Application February 11,1942, Serial No. 430,465 In Great Britain February 7, 1941 7 Claims.

The invention relates to electrical contact mechanisms and, moreparticularly, to those which in operation are continuously closed andopened. i

It is an object of this invention to ensure reliable operation of suchcontact mechanisms, particularly by eliminating. faults due to irregularspacing of the contacts which may either be too widely spaced or tend tostick together.

It is another object of the invention to improve existing contactmechanisms of this character, an d,to effect repair thereof cheaply andeasily andwithout dismantling, when they are worn.

It is still another object of the invention to make it possible todispense with the use of precious metals such as platinum or specialalloys such as tungsten alloys for the contacts or points thereof, andto obtain satisfactory operation with cheaper and less rare metals.

A preferred application of the invention is its use in connection withfractional horsepower electro-motors having an armature which is notconnected to any outer circuit. In such motors The invention furthercomprises in a controlsystem for a small electric motor, an electriccontact mechanism for controlling the winding.

of said motor by opening and closing the circuit of said windingsynchronously with the rotation of said motor, comprising a pair ofmaincontacts adapted continuously to make and break said circuit, and anintermediate contact resiliently located between said main contacts.

The invention further comprises an electric contact mechanism comprisinga pair of main contacts adapted continuously to make and break circuitby both moving simultaneously away from and towards one another, and anintermediate contact located resiliently between said main contacts.

In the accompanying drawing an embodiment of the invention as applied tothe contact mechanism of a fractional horsepower motor of a dry shaveris shown by way of example. The lid or cover of the dry shaver is shownremoved.

The insulating casing of the appliance is denoted I, the fixed andreciprocating cutters 2, 2. 3 are the coils of the field electromagnets4, and 5 is the armature which rotates on shaft 6 carrying the cam l.Coils 3 are.supplied with current through the plug and socket connection8 and flex 9. On the other hand the coils 3 are connected to theresilient contact blades I0 forming a make and break mechanismcontrolled by the cam l which bears on the insulating strips ll fixed tosaid blades causing said blades to move towards and away from eachother, separating only a short distance.

When the contact ends of blades l!) are worn out they may either sticktogether thus failing to break contact or they may be too far remote formaking contact at all. By inserting an independent resilient tongue l2of simple leaf spring formation (i. e. supported at one end and entirelyfree at the other) preferably carrying a contact piece l3 at its freeend between the main contacts of the blades ID th above mentioneddifficulties were overcome without any mending cf the main contactsthemselves.

The resilient tongue l2 was attached to a bar M which, in turn, wasconnected to a thin plate I5 clamped between the insulating casing l andthe likewise insulating lid (not shown) of the dry shaver, by means ofone of the clamping screws I 6,

In operation the tongue l2 cscillated between, and independent of, thecam operated blades I0 alternatively making contact with both of themsimultaneously, and breaking contact with at least one of them. It couldbe observed that the sparks Were continuously changing their places thusspreading the inevitable wear over the whole surface of the contacts.Accordingly a dry shaver which had become inoperative through itsspecial alloy contacts being burnt out was put into, and kept in,improved operation for many weeks by inserting an ordinary brass contactpiece between the burnt main contacts.

Starting of fractional horsepower-motors of this kind which hitherto hadto be eifected by twisting the armature shaft could now be obtainedsimply by switching on the current as the independent oscillation of thetongue sufficed al-- ready at certain angles for the initial breaking ofthe contact.

It has been found particularly advantageous to make the intermediatecontact end in a sharp edge. This seems to have a favourable influenceon the breaking ofthe sparks between the contacts.

The tongue 12 could be of conductive material and fixed to an insulatingpoint or it could be made of insulating material and carry a conductivecontact piece only. In this case it could be fixed to a Iron-insulatedpoint, if desired.

The tongue could be inserted without any alterations into an existingdry shaver by the user himself or by any non-skilled shopkeeper or shopassistant which made it unnecessary to send the appliance to a specialrepair work shop. or course in the design of new appliances provisioncan be made for arranging a resilient tongue which would increase thevalue of the dry shaver for the owner who would even prefer to pay anincreased purchase sum to gain the advantage of having the uninterrupteduse of his appliance, and of saving costs for its repair.

Although the invention is described with reference to dry shavers itsscope reaches beyond that of such and similar appliances as e. g.electrical hair cutters for men and animals. The invention may beapplied to all electric contact mechanisms, particularly to thosecontinuously actuated by mechanical or electrical means, such as withscreen wipers, light signals or electric ignition circuits of internalcombustion engines. The tongue according to the invention may even beapplied between the brushes and worn out commutators of electromotors ordynamos.

What I claim and desire to secure by Letters Patent is:

1. An electric circuit controlling mechanism, comprising a pair ofspaced, relatively movable main contacts connected in a common circuit,an auxiliary contact member disposed between said main contacts forcommon engagement therewith but normally spaced therefrom, saidauxiliary contact member being yieldingly mounted so as to be freelymovable with either of said main contacts on engagement therewith onopening and closing of the common circuit, and means for relativelymoving said main contacts towards and away from each other and into andout of common engagement with the intermediate auxiliary contact memberto respectively close and open the common circuit aforesaid through theintermediate auxiliary contact member, said auxiliary contact memberbeing normally wholl outside of said common circuit except when inengagement with the main contacts.

2. An electric contact mechanism, comprising a pair of main contactsconnected in a common circuit, an intermediate auxiliary contact deviceof simple leaf spring formation (that is supported at one end andentirely free at the other) located between said main contacts, andmeans for producing continuous relative vibratory electrical connectionbetween said main contacts is continuously made and broken through saidintermediate auxiliary contact device whereby said common circuit iscontinuously established and disestablished.

3. An electric contact mechanism, comprising a pair of main contactsconnected in a common circuit, an intermediate auxiliary contact devicemovement between said main contacts whereby tact device being entirelydisconnected from the I aforesaid common circuit save for its functionin establishing said common circuit.

4. An electric contact mechanism, comprising a pair of main contactsconnected in a common circuit, an intermediate auxiliary contact deviceof simple leaf spring formation (that is supported at one end andentirely free at the other) located between said main contacts, andmeans for continuously vibrating both of said main contactssimultaneously away from and toward one another whereby electricalconnection between said main contacts is continuously made and brokenthrough said intermediate auxiliary contact device, whereby said commoncircuit is continuously established and disestablished.

5. An electric contact mechanism, comprising a pair of main contactsconnected in a common circuit, an intermediate auxiliary contact deviceof simple leaf spring formation (that is supported at one end andentirely free at the other) located between said main contacts, andmeans for producing continuous relative vibratory movement between saidmain contacts whereby electrical connection between said main contactsis continuously made and broken through said intermediate auxiliarycontact device whereby said common circuit is continuously establishedand disestablished, said intermediate contact being so arranged that atsome period during the vibratory cycle said auxiliary intermediatecontact is free from both main contacts.

6. An electric contact mechanism comprising a pair of main contactsconnected in a common circuit, an intermediate auxiliary contact deviceconsisting of a flexible strip of insulating material carrying at itsfree end a contact located between said main contacts, and means forproducing continuous relative vibratory movement between said maincontacts whereby electrical connection between said main contacts iscontinuously made and broken through said intermediate auxiliary contactdevice whereby said common circuit is continuously established anddisestablished.

7. In a control system for a small electric motor, an electric contactmechanism comprising a pair of main contacts connected in circuit withsaid motor, an intermediate auxiliary contact flexibly mounted betweensaid main contacts, and means for producing continuous relativevibratory movement between said main contacts in synchronism with therotation of said motor whereby electrical connection between said maincontacts is continuously made and broken through said intermediateauxiliary contact and the motor circuit is continuously established anddisestablished.

WERNER ARON.

